Electric current rectifying device



Feb. 12, 1935- A. GAUDEN ZI ETAL ELECTRIC CURRENT RECTIFYING DEVICEFiled July 2, 1929 Inventors Arthur Gaudenzi Stephan Widmer Julius JonasV A ztorngy Patented Feb. 12, 1935 UNITED STATES ELECTRIC CURRENTRECTIFYING DEVICE Arthur Gaudenzi, Stephan Widmer, and Julius Jonas,Baden, Switzerland, assignors to Aktiengesellschaft Brown Boveri & Cie,Baden, Switzerland, a joint-stock company of Switzerland ApplicationJuly 2, 1929, Serial No. 375,550 In Germany July 13, 1928 6 Claims.

This invention relates to improvements in electric current rectifyingdevices of the metallic vapor type in which an electric arc flows froman anode to a cathode.

Electric power rectifiers require a large are at a high temperaturewhich vaporizes excessive amounts of the material from the cathode ofthe structure, which is usually a liquid metal such as mercury, whichexcessive amounts of vapor create a high vapor density in the operatingspace. Such vapor density is likely to cause condensation of some of themetallic vapor on the anodes thereby forming a so-called cathode spotwhich, at such time, when it is negative with respect to the cathode,permits a reverse flow of current or socalled backfiring. Suchbackiiring causes disturbances in the circuit to which theelectric'rectifying device is connected and may even lead to destructionof the rectifying structure itself.

The above problem may be solved by either one of two methods or by acombination of these two methods, both of which have the common objectof reducing the vapor density ahead of the anodes and thereby decreasingthe danger of formation of a cathode spot thereon. The amount of vaporin the operating space ahead of the anodes may be reduced byenclosingthe anodes in are guides which are heated directly adjacent tothe anode or are cooled at the aperture through which the metallic vaporflows. It will be understood, of course, that the two methods may becombined to further decrease the vapor density during operation of thedevice.

It is, therefore, among the objects of the present invention to providean electric current rectifying structure which will reduce the amount ofmetallic vapor directly ahead of the anodes therein. 9 l

Another object of the invention is to utilize a cooling means and aheating means to reduce the vapor density within the operating spaceahead of the anodes of a metallic vapor rectifier.

Another object of the invention is to provide a structure in whichcooling means are arranged about or directly ahead of the entrance intothe anode operating space and in which heating means are arrangedwithinthe operating space adjacent the anode.

Objects and advantages, other than those above set forth, will beapparent from the following description and the drawing in which Figure1 is a vertical cross-sectional view of an electric current rectifier ofthe metallic vapor type showing one embodiment of the present invention,and

Figs. 2, 3, 4, 5, and 6 are fragmentary views of Vertical cross-sectionssimilar to that shown in Fig. 1, but showing modified embodiments of thepresent invention.

Referring more particularly to the drawing by characters of reference,reference numeral? indicates a double walled tank portion having acathode well 8 in the bottom portion thereof, which well is arranged ininsulated relation tothe other portions of the tank. Tank '7 is formedwith double walls to provide a path for the circulation of coolingmedium therethrough. Cathode well 8 is arranged to receive a quantity ofa liquid metal,

such as mercury, which forms a cathode 9. The tank is closed by a tankcover or top plate 11 having apertures therethrough to receiveinsulating members 12 through which anodes 13 extend into the interiorof tank 'l. Arc guides 14, which are generally formed of metal, arearranged in insulated relation about the anodes 13 to form an operatingspace directly ahead of each anode and to serve as means for confiningand directing the arc flowing from the anodes to the cathode. The amountof metallic vapor, which forms the conductor for the arc, flowing intoare guides 14 is reduced by heating the space, directly adjacent theanode by a heating element 16 and by cooling the aperture into the areguides 14 by the use of cooling chambers 17 which may be secured to thearc guides 14 by means of insulators 1'8-or may be secured thereto inuninsulated relation, as may be desired. The heating element may bearranged either within or without the arc guides as may be desired.

Providing the use of a separate heating element isundesirable, agrid-like member 19 may be arranged within are guides 14 ahead of anodes13. The are flowing through the are guides from the anodes to thecathode is of such high temperature that sufficient heat is extractedtherefrom by screen 19 to maintain the space ahead of the anodes insubstantially heated condition both during the time in which the anodeis in operation and during the time in which no current is flowingtherethrough. Anodes 13 may themselves be heated by a special separateheating means or they may be heated by overloading in which case it isnecessary that they be capable of resisting disintegration at hightemperatures.

The cooling members 17 may also be supported in spaced relation on thebottom of tank '7, by means of insulating supports 21, immediately aheadof the aperture into are guides 14, if a greater cooling and increasedcondensation of the metallic vapor is desired before the vapor flowsinto the arc guides. For multi-anode rectifiers, the arc guides may beconductively connected with the cooling medium supply conductor whilethe cooling members are connected in insulated relation thereto for thepurpose of maintaining the proper potential relations in the severalportions of the structure.

The are guides 14 may also be extended into close proximity with thebottom of tank 7 which is formed with double walls through which a tionof a substantial portion of the vapor which returns to the cathode andis prevented from entering the operating space within the are guides.The metallic vapor flowing into the arc guide is again superheated bycontact with the heating element or the grid and is forced, byexpansion, into contact with the cooling members where a furtherquantity thereof is condensed and returned to the cathode.

The cooling action of the bottom of tank 7 and diminishing of themetallic vapor may be increased by securing a plurality of heat transfersurfaces thereto such as are indicated by the cooling ribs 22 shown inFig. 5. Such structure provides for a more intimate contact of themetallic vapor with the cooled bottom wall surface and thereby increasesthe amount of vapor condensed by contact therewith especially when thecross-section area of the guides is somewhat diminished adjacent thelower end thereof. Ex-

tensions 23 may be formed on cooling ribs 22 to extend into the aperturein are guides 14 to in crease the cooling effect at the point at whichthe metallic vapor .must pass before flowing into the operating spacefor the anodes directly adjacent the grids 19. The cooling ribs, whenarranged directly beneath the arc guides, serve to assist indirectingthe flow of the arc. The

ribs are preferably arranged radially over the entire bottom of the tankin uniformly spaced relation.

a It will be apparent that the amount of metallic. vapor flowing intothe are guides and the vapor density ahead of the anodes issubstantially decreased by the present invention without increasing thepotential drop in the arc. The danger of the formation of cathode spotson the anodes with the resultant backfiring is therefore materiallydecreased which greatly increases the reliability and stabilityof thedevice.

Although but one embodiment has :been. illustrated and described, itwill be understood that various other embodiments are possible, and thatvarious changes may be made without departing from the spirit of theinvention or thescope of the claims- The invention claimed is:

1. In an electric current rectifying device, a

double walled tank providing a path for the circulation of a a coolingmedium between the spaced walls thereof, a cathode retained within saidtank, anodes extending into said tank, are guides partially enclosingsaid anodes,grids capable of extracting heat from the arc flowingbetween said cathode and said anode, said grids being arranged withinsaid guides directly ahead of said anodes for heating the anode space,and

into said container, are guides surrounding said" anodes, means disposedwithin said guides and adjacent said anodes operative to elevate thetemperature of the space about. the anodes,

and means supported within said container adjacent said guides operativeto simultaneously effect condensation of vapor flowing from said cathodetowards said anodes by way of said guides.

3. In an electric current rectifying device, a container, a cathode ofvaporizable material retained within said container, anodesextendinginto said container, arc guides partially enclosing saidanodes, means supported by said guides for elevating the temperature ofthe space about the anodes, and means supported within said containeradjacent said guides operative to simultaneously effect condensation ofvaporized cathode material tending to flow towards said anodes by way ofsaid guides. V

4. In an electric current rectifying device, a container comprisingspaced walls providing a path for the circulation of cooling mediumtherebetween, a cathode comprising a vaporizable material retainedwithinsaid container, anodes extending within the said container, guidespartially enclosing and constituting a channel for the flow of arcs fromthe anodes to the said cathode, means individual to and supported-bysaid guides operative to elevate the temperature of the space about theanodes therein, and means'disposed within said container adjacent saidguides operative to extract and transmit to the said container walls theheat from vaporized cathode way of said guides.

5. In an electric current rectifying devicaa container comprising meansproviding a path for the circulation of a cooling medium'thereabout, acathode comprising a vaporizable material retained within saidcontainer, anodes ex tending into said container, guides partiallyenclosing and supported by said anodes in insulated relation theretohaving an open end constituting a passage for the flow of arcs from the,

anodes to the said cathode, means supported by said guides operative toelevate the temperature of the space therein about the anodes, and meansaflixed to wall portions of said container and extending therefrom topositions. adjacent said guides operative to simultaneously. extract andtransmit to said wall portions heat from vaporized cathode materialtending to flow to-, wards said anodes by way of said open ends of saidguides. V v V 6. In an electric current rectifying device, a closedcontainer, a plurality of anodes extending within said container, acathode comprising a vaporizable material contained within said con- Ytainer, an arc guide surrounding each said anode having an openingtherein constituting a chan nel for theflow therethroughof vapor fromsaid cathode toward the associated anode, means disposed within saidcontainer adjacent thesaid opening of each of said guides operative toeffect the condensation of said vapor flowing towards said anodes, andmeans disposed within each said guide operative to simultaneouslyelevate the temperature of the space about the anode surrounded thereby.I

ARTHUR GAUDENZI.

STEPHAN WIDMER. JULIUS JONAS.

